This invention relates to automatic implantable devices to detect and differentiate between tachycardias (rapid heart rhythms) for diagnostic purposes or in order to therapeutically stimulate the heart. The invention relates more specifically, to devices which analyze the rhythm of both the atrium and ventricle in order to distinguish among tachycardias and have the capability of treating both ventricular and supraventricular tachyarrhythmias.
The article "Automatic Tachycardia Recognition" by R. Arzbaecher et al., PACE, May-June 1984, pp. 541-547, discloses an algorithm implemented in a microprocessor based implantable device employing both atrial and ventricular rate detection via separate bipolar leads in order to measure the AA and VA, or VV and AV intervals in order to distinguish among various types of tachycardias. The Arzbaecher et al. article also discloses the concept of employing a single atrial extra stimulus to distinguish sinus tachycardia from 1:1 paroxysmal tachycardia.
Other proposals for employing atrial and ventricular detection and interval comparison are set forth in The Third Decade of Cardiac Pacing: Advances in Technology in Clinical Applications, Part III, Chapter 1, "Necessity of Signal Processing in Tachycardia Detection" by Furman et al. (edited by S. Barold and J. Mugica, Futura Publications., 1982, pages 265-274) and in the Lehmann U.S. Pat. No. 4,860,749. In both cases, atrial and ventricular rates or intervals are compared to one another in order to distinguish sinus and pathological tachycardias.
A recent article, "MATIC--An Intracardiac Tachycardia Classification System" by Leong et al , PACE, Vol 15, September 1992, Pages 1317-1331, disclosed an automated tachycardia analysis system which employs a neural network for morphology analysis and which compares measured A-V intervals to measured V-V intervals for classification of tachycardias displaying 1:1 correspondence between atrial and ventricular depolarizations.